Remote indicating or control system



Jan; 23, 1945. A c, DENISOFF 2,367,845

REMOTE INDICATING OR CONTROL SYSTEM Filed March 11, 1944 2 Sheets-Sheet 1 flow ATTUEZYE'Y Jan. 23, 1945. A. c. DENISOFF 2,367,845

REMOTE INDICATING OR CONTROL SYSTEM Filed March 11, 1944 2 Sheets-Sheet 2 Patented Jan. 23, 1945 REMOTE INDICATING OR CONTROL SYSTEM Alexander Constantine Denisoif, St. Margarets, East Twickenham, England. assignor to The Liquidometer Corporation, Long Island City, N. Y.. a corporation of Delaware Application March 11, 1944, Serial No. 526,079 In Great Britain November 11, 1942 2 Claims. (Cl. 177-380) This invention relates to an electric remote indicating or control system of the kind in which the transmitter consists of a closed resistive path, which is provided with three or more equally spaced fixed tapping points which are connected with the receiver, and which is traversed by two moving brushes, each connected to one pole of a suitable source of potential, In the case where the resistive path is in the form of a circle and .the brushes are free to move over the full 360 the receiver which may be of the resultant field type may reproduce the movement of the brushes over the same angle. Where however the resistance is arranged to be linear or arcuate, the movement of the brushes is limited to one half the length, the brushes being necessarily spaced apart on the resistance by this amount, and normally only a 180 movement at the receiver can be obtained.

It is one object of the present invention to pro vide an improved transmitter which shall have a limited brush movement and at the same time provide a full 360 movement at the receiver.

In accordance with the present invention the Improved transmitter comprises a single resistive element of linear or arcuate form and a central brush, and two outer brushes, which are movable as one over the resistive element, the outer brushes being equally spaced from the central brush by one half the length of the element and connected electrically together.

One form of the invention is illustrated in the accompanying drawings in which Fig. 1 is a plan view of a transmitter adapted to be operated by a float;

Fig. 2 is a vertical section taken on the line 2-2 in Fig. 1 looking in the direction of the arrows, and

Fig. 3 is an electrical wiring diagram of the transmitter, a receiver and the connections therebetween.

Referring to Figs. 1 and 2 there is shown a transmitter comprising a housing II which is adapted to be mounted on the side wall of a liquid container by means of a flange I2. The housing I I extends into the interior of the liquid container and is provided on its rear end with a fixed pivot I3 about which a float arm I 4 may rotate. In the interior of the housing II is a base plate I5, moulded of insulating material, which supports a fixed spindle IE on which a brush carrier ll of insulating material is rotatably mounted. Movement of the brush carrier I'I about its pivot I6 may be effected in any suitable manner (not shown) in response to any condition which it is desired to indicate in accordance with this invention, as otherwise described herein. For details of a suitable arrangement for this purpose reference may be had to British patent specification 471,224. Also mounted on the base plate I5 is an arcuate resistance strip I 8. The carrier I'I supports three brushes I9, 20 and 2I, so that as it rotates under the infiuence of the float arm I 4 the ends of the brushes move over the resistance strip I8 in contact therewith. The centre brush 20 is secured to the carrier I! by a rivet 22 and extends over the axis of the pivot I6 where it makes contact with one end of a fixed contact strip 23, the other end of which is secured to the base plate I5 by screw 24 which also forms one of the terminals of the transmitter. The two outer brushes I9 and 2I are also secured to the carrier H by rivets 25 and 26 respectively and they are connected together electrically by a bridge piece 21 which passes over the brush 20 and also extends over the axis of the pivot I6 where contact is made with one end of a contact strip 28, the other end of which is secured to base plate I5 by terminal screw 29. Terminal screw 30 is connected electrically with each end of the resistance strip I8 as diagrammatcally indicated by the dotted lines, while termi-*- nal screws 3I and 32 are connected respectively with tapping points arranged on the resistance strip at distances of one third and two thirds of its length respectively from one end. Adjustment of these tapping points is effected by means of contact strips 33 which at one end make contact with the strip and, at the other end, are pivotally mounted on the base plate I5 by screws 34, the strips 33 being adjustable through a limited range by screws 35 which are formed with an eccentric engaging a hole formed in the strip. For further details of this method of adjustment reference may be made to British patent specification No. 483,450. If desired similar adjustable contact strips (not shown) may be provided for making connection between the ends of the resistance strip I8 and the terminal 30.

Referring now to Fig. 3 there is shown a wiring diagram of a electrical indicating system in which the transmitter T corresponds to the transmitter described with reference to Figs. 1 and 2 like parts being indicated by the same reference numerals.

The receiver R, which may be of any suitable type, is as shown a ratiometer having three defiecting coils 38, 39 and 40 connected in delta formatio which control the position of a. magnetized rotor to which an indicating pointer may be connected. One suitable instrument of this type is shown in British patent specification No. 548,447. Transmitter T and receiver R are connected together by a five conductor cable such that the junction points of the deflecting coils 38, 39 and 40, which are connected with terminals 4|, 42 and 43, are connected through terminals 32, 30 and 3| respectively at the transmitter with the tappings on the resistance strip, while a source of potential connected with terminals 44 and 45 at the receiver is connected through limiting resistances 46 and 41, terminals 48 and 49 and terminals 24 and 29 respectively at the transmitter with the brushes 20 and I9, 2|.

The operation of the system is as follows. With the brushes of the transmitter in the position shown in Fig. 3 which may represent the position they take up When the float is in its lowest position, movement of the float to its highest position may be arranged to cause the brush 20 to move to the other end of the resistanc strip l8. For the first half of this movement the brush l9 will move from the position shown to the upper end of the resistance strip l8 and during the second half of 'this movement of the brush 20, as soon as the brush 1!! leaves the upper end of the resistance strip, the brush 2 I makes contact with the lower end of the resistance strip l8 and moves up to the position occupied by the brush 19 at the beginning of the movement.

Electrically the transmitter is exactly equivalent to the known type of transmitter having a resistance strip extending in a complete circle and two brushes spaced apart by 180 in which a 360 movement of the brushes produces a 360 movement of the receiver. So in the arrangement of the present invention a movement of the brush 20 from one end of the resistance strip IE to 'the other will produce a 360 movement at the the indicating instrument, the movement of the float from maximum to minimum, which in different installations is variable, has always to be translated, e. g, by gearing into a 360 rotation of the brushes, the arrangement in accordance with the present invention oflers considerable advantages in that by adjusting the length of the resistance strip in use, the position of the fixed tapping points, and the distance between the brushes, any desired movement of the latter under the influence of the float arm may be caused to provide a full 360 movement of the indicator.

Where the transmitter has to present a particular resistance to th source of supply, the resistance of the strip may be kept at a fixed value and extra resistance, mounted in the transmitter head, inserted in the connection between the brushes and the terminals to which is connected the source of supply.

I claim:

1. A transmitter for an electrical indicating or control system comprising a single resistive element of linear or arcuate form, and a central brush and two outer brushes which are movable as one over the resistive element, the outer brushes being equally spaced from the central brush by one half of the length oi the resistive element and directly connected electrically together within the transmitter.

2. A transmitter for an electrical indicating system comprising a resistive element of linear or arcuate form provided with three terminals adapted for connection with the three terminals of a receiver comprising a ratiometer having three deflecting coils, the said terminals being constituted respectively by the junctions of the ends of the resistive element and tapping points arranged at one third and two thirds of its length, and three brushes, movable as one over the element and spaced thereon by a distance equal to one half of the length of the element, the central brush being adapted for connection with one terminal of a source of supply and the other two brushes being connected with one another and adapted for connection with the other terminal of the source of supply.

ALEXANDER CONSTANTINE DENISOFF. 

